Vasculitides are heterogenic group of autoimmune connective tissue diseases which often present difficulties in early diagnosing. Giant cell arteritis is vasculitis of large and medium arteries. It predominantly presents with symptoms of affection of the external carotid artery branches. Furthermore, the only symptoms can be constitutional. In clinical practice, vasculitides are sometimes considered as paraneoplastic, but no definite association with malignancies has been established and the mechanisms are still debated. The gold standard for diagnosing giant cell arteritis is a positive temporal artery biopsy, but the results can often be false negative. Additionally, more than half of the patients have aorta and its main branches affected. Considering aforementioned, imaging studies are essential in confirming large-vessel vasculitis, amongst which is highly sensitive PET/CT. We present the case of a 70-year-old female patient with constitutional symptoms and elevated sedimentation rate. After extensive diagnostic tests, she was admitted to our Rheumatology unit. Aortitis of the abdominal aorta has been confirmed by PET/CT and after the introduction of glucocorticoids the disease soon went into clinical and laboratory remission. Shortly after aortitis has been diagnosed, lung carcinoma was revealed of which the patient died. At the time of the comprehensive diagnostics, there was no reasonable doubt for underlying malignoma. To the best of our knowledge, there are no recent publications concerning giant cell arteritis and neoplastic processes in the context of up-to-date non-invasive diagnostic methods (i.e. PET/CT). In the light of previous research results, we underline that the sensitivity of PET/CT is not satisfactory when estimating cancer dissemination in non-enlarged lymph nodes and that its value can at times be overestimated.